<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #p1 {
            color: red;
        }

        .c1 {
            color: green;
        }
        a,#p1,.c1{
            background-color: aqua;
        }
        input[type=text]{color: red}
        input[type=password]{background-color: coral}
        /*任意元素选择器,可以操作所有元素*/
        *{border: 1px solid red;}
    </style>
</head>
<body>
<input type="text">
<input type="password">
<a href="">超链接</a>
<p id="p1">苹果</p>
<p>香蕉</p>
<p class="c1">菠萝</p>
<div>电视</div>
<div>冰箱</div>
<div class="c1">洗衣机</div>
</body>
</html>